Fri·Oct 23, 2015Friday·October 23, 2015

1. 01*

   Measurement of spin-flip probabilities for ultracold neutrons interacting with nickel phosphorus coated surfaces

   Z. Tang🇺🇸 · E. R. Adamek🇺🇸 · A. Brandt🇺🇸 · N. B. Callahan🇺🇸 · S. M. Clayton🇺🇸 · S. A. Currie🇺🇸 · T. M. Ito🇺🇸 · M. Makela · Y. Masuda🇯🇵 · C. L. Morris🇺🇸 · R. Pattie Jr.🇺🇸 · J. C. Ramsey🇺🇸 and 3 other authors

   We report a measurement of the spin-flip probabilities for ultracold neutrons interacting with surfaces coated with nickel phosphorus. For 50~$\mu$m thick nickel phosphorus coated on stainless steel, the spin-flip probability per bounce was found to be ${\beta }_{\mathrm{NiP}\mathrm{on}\mathrm{SS}}=(3.3_{-5.6}^{+1.8})\times 10^{-6}$. For 50~$\mu$m thick nickel phosphorus coated on aluminum, the spin-flip probability per bounce was found to be ${\beta }_{\mathrm{NiP}\mathrm{on}\mathrm{Al}}=(3.6_{-5.9}^{+2.1})\times 10^{-6}$. For the copper guide used as reference, the spin flip probability per bounce was found to be ${\beta }_{\mathrm{Cu}}=(6.7_{-2.5}^{+5.0})\times 10^{-6}$. The results on the nickel phosphorus-coated surfaces may be interpreted as upper limits, yielding ${\beta }_{\mathrm{NiP}\mathrm{on}\mathrm{SS}}<6.2\times 10^{-6}$ (90\% C.L.) and ${\beta }_{\mathrm{NiP}\mathrm{on}\mathrm{Al}}<7.0\times 10^{-6}$ (90\% C.L.) for 50~$\mu$m thick nickel phosphorus coated on stainless steel and 50~$\mu$m thick nickel phosphorus coated on aluminum, respectively. Nickel phosphorus coated stainless steel or aluminum provides a solution when low-cost, mechanically robust, and non-depolarizing UCN guides with a high-Fermi-potential are needed.

   nucl-exphysics.ins-detNucl.Instrum.Meth.A(2016)·15 citations
2. 02*

   Extended Skyrme interactions for nuclear matter, finite nuclei and neutron stars

   Zhen Zhang🇺🇸 · Lie-Wen Chen🇨🇳

   Recent progress in theory, experiment and observation challenges the mean field models using the conventional Skyrme interaction, suggesting that the extension of the conventional Skyrme interaction is necessary. In this work, by fitting the experimental data of a number of finite nuclei together with a few additional constraints on nuclear matter using the simulated annealing method, we construct three Skyrme interaction parameter sets, namely, eMSL07, eMSL08 and eMSL09, based on an extended Skyrme interaction which includes additional momentum and density dependent two-body forces to effectively simulate the momentum dependence of the three-body force. The three new interactions can reasonably describe the ground-state properties and the isoscalar giant monopole resonance energies of various spherical nuclei used in the fit as well as the ground-state properties of many other spherical nuclei, nicely conform to the current knowledge on the equation of state of asymmetric nuclear matter, eliminate the notorious unphysical instabilities of symmetric nuclear matter and pure neutron matter up to a very high density of $1.2$ fm${}^{-3}$, and simultaneously support heavier neutron stars with mass larger than two times solar mass. One important difference of the three new interactions is about the prediction of the symmetry energy at supra-saturation densities, and these new interactions are thus potentially useful for the determination of the largely uncertain high-density symmetry energy in future. In addition, a comparison is made for the predictions of nuclear matter, finite nuclei and neutron stars with the three new interactions versus those with three typical interactions BSk22, BSk24 and BSk26 from Brussels group.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2016)·47 citations
3. 03*

   Heavy flavor electron $R_{\text{AA}}$ and $v_2$ in event-by-event relativistic hydrodynamics

   Caio A G Prado🇧🇷 · Mauro R Cosentino🇧🇷 · Marcelo G Munhoz🇧🇷 · Jorge Noronha🇧🇷 · Alexandre A P Suaide🇧🇷

   In this work we investigate how event-by-event hydrodynamics fluctuations affect the nuclear suppression factor and elliptic flow of heavy flavor mesons and non-photonic electrons. We use a 2D+1 Lagrangian ideal hydrodynamic code on an event-by-event basis in order to compute local temperature and flow profiles. Using a strong coupling inspired energy loss parametrization on top of the evolving space-time energy density distributions we are able to propagate the heavy quarks inside the medium until the freeze-out temperature is reached and a Pythia modeling of hadronization takes place. The resulting D${}^0$ and heavy-flavor electron yield is compared with recent experimental data for $R_{\text{AA}}$ and $v_2$ from the STAR and Phenix collaborations. In addition we present preditions for the higher order Fourier harmonic coefficients $v_3(p_T)$ of heavy-flavor electrons at RHIC's $\sqrt{S_{\text{NN}}}=200$ GeV collisions.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2016)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.